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Scientific Report 2007-2009
Particle physics
• BaBar at PEPII at Stanford (USA)
• CDF at Tevatron in Fermilab, Chicago (USA)
• MEG at PSI, Villigen (Switzerland)
• ZEUS at DESY, Hamburg (Germany)
• UA9, NA62, ATLAS, ALICE, CMS, LHCb at the European laboratory of CERN, Geneva
(Switzerland)
• KLOE at DAΦNE in Laboratori Nazionali di Frascati (INFN)
• VIRGO at EGO facility in Cascina (INFN-IN2P3)
• CUORE, DAMA, OPERA at Laboratori Nazionali del Gran Sasso (INFN)
There are also important activities in space (AMS) and underwater (ANTARES, NEMO)
1.1 Particle Physics with Accelerators
The search of new particles and new phenomena is the core of this field of activity. It is performed
usually by large collaborations operating at large hadronic or e + e − colliders. After the success
of the Standard Model validated by the precision measurements carried on at LEP two lines of
research eventually developed. One is based on hadron colliders operating at the energy frontier
(Tevatron at Fermilab, LHC at CERN) and the other is exploiting the intensity frontier (DAΦNE
at LNF, PEPII at SLAC, the fixed target program at CERN SPS). The main goals of research
at the energy frontier are the precision measurements of top quark parameters, the search for
rare or new processes like the production of the Higgs boson and the ’Supersymmetry’ (in an
extended meaning). The intensity frontier is used to exploit the flavour physics studying the CP
violation, both on K- and B-mesons and for precision measurements of the quark couplings (the
CKM paradigm).
1.1.1 The Energy Frontier
The Tevatron collider has now collected almost 8 fb −1 of integrated luminosity and is expected to
reach 10 fb −1 by the end of 2011. Members of the Physics Department of the Sapienza University,
taking advantage of the large data sample available, have been involved within the CDF collaboration
in searches of rare processes as like pair production of W and Z bosons and the production
of heavy flavor jets in association with W or Z [P10]. Recently, the proton-proton collider LHC
has successfully reached the center of mass energy of 7 TeV, the maximum energy ever reached by
a particle accelerator (see Fig. 1). Such a high energy allows to significantly extend the capability
to discover new phenomena at the TeV energy scale. The machine is now improving its intensity
in order to match the luminosity requirement for studying rare phenomena like possible Higgs
boson production and decay, and search for supersymmetric particle production.
Six experiments are operating in the four LHC interaction regions. The two main experiments,
ATLAS and CMS, are detectors of unprecedented dimensions and complexity, aiming to exploit
all what is connected to the energy frontier. They have been designed and realised to detect all
particles produced in the interaction, and to reconstruct the kinematics of the interesting events.
Due to the 40 MHz bunch crossing frequency, to the very large expected luminosity and to the
total cross section of pp collisions, the trigger systems of these experiments have to identify the
few interesting events (of the order of 100 Hz) in a very short time out of an interaction rate of
more than 100 MHz. The project and realization of the trigger detectors and systems has been a
particularly challenging enterprise.
Sapienza Università di Roma 102 Dipartimento di Fisica